Flying mammals from Jurassic suggest early diversification

The newly discovered fossils are haramiyidans, long-extinct cousins of modern-day mammals. They are beautifully preserved, showing wing-like skin membranes between their front and back limbs.

In two papers published this week in the journal Nature, an international team of scientists describes two 160-million-year-old fossils found in China showing that the ancestors of mammals in the Jurassic period had evolved wing-like limbs that allowed them to glide.

The two species, Maiopatagium furculiferum and Vilevolodon diplomylos, were discovered in the Tiaojishan Formation northeast of Beijing, and are the oldest known gliders among early mammals. Modern volant mammals include flying squirrels and bats.

"These Jurassic mammals are truly 'the first in glide,'" said co-author on both papers, Zhe-Xi Luo, a professor of organismal biology and anatomy and the University of Chicago, in a statement. "In a way, they got the first wings among all mammals."

The newly discovered fossils are haramiyidans, long-extinct cousins of modern-day mammals. They are beautifully preserved, showing wing-like skin membranes between their front and back limbs.

"It's amazing that the aerial adaptions occurred so early in the history of mammals," said co-author David Grossnickle, a graduate student at the University of Chicago. "Not only did these fossils show exquisite fossilization of gliding membranes, their limb, hand and foot proportion also suggest a new gliding locomotion and behavior."

The new fossil gliders indicate that early mammals exhibited a broad range of ecological diversity, which suggests "dinosaurs likely did not dominate the Mesozoic landscape as much as previously thought," Luo said